Technique of local probabilistic tsunami zonation for near-field seismic sources applied to the Bechevinskaya Cove (the Kamchatka Peninsula)

Currently, the most popular approach for assessing the tsunami hazard on a coast is the PTHA (Probabilistic Tsunami Hazard Assessment). In this preliminary study, we develop one of the variants of the SPTHA (Seismic PTHA) method, adapted to solving local tsunami zonation problems for near-field sources. The approach is applied to assessing the tsunami hazard of the Bechevinskaya Cove located on the eastern coast of the Kamchatka Peninsula in the northern part of Avachinsky Bay. We propose the method, algorithms and results of probabilistic assessment of the cove's tsunami hazard in order to determine the safest water areas, in which the values of the intensity measures (IMs) of tsunami will not exceed the specified threshold values with the given Average Return Periods (ARPs). The method includes analysis of seismotectonics of the region, construction of a catalog of model tsunamigenic earthquakes, determination of their statistical characteristics, scenario numerical modeling of the dynamics of tsunami waves, calculations of the values of IMs that can be exceeded with the given annual rates (ARs), namely, on average 1 time in 100, 500, 1000 years. Spatial distributions of the maximum wave heights and maximum velocities are provided for the ARs. Three configurations of the water area are considered, including the possibility of constructing protective structures, and conclusions are drawn about their influence on the tsunami hazard assessments in the cove.